Large, straight and branched chain alkanes (waxes) have a tendency to separate from fuels and oils due to their tendency to crystallize at low temperatures and on standing. This is undesirable because separation impairs the desirable properties of the base oil or fuel oil, particularly its ability to flow. Additives may be used to minimize or inhibit the undesirable effects associated with wax crystallization as well as to impart desirable properties to base oils or fuels or to enhance existing beneficial properties. In order to accomplish this they must interact with the waxy components of the oil. Thus, the structural properties of flow improvers require the presence of a portion of the molecule which resembles that of the wax, i.e., a sequence of consecutive CH.sub.2 units that are sufficient to impart wax-like properties to the unit or molecule. In addition, the presence of some feature or features which do not resemble the wax is required. This allows the flow improver to interact with the growing wax crystal and bind to its surface, but to interrupt further growth of the wax crystal. For example, additives can alter the crystalline properties of waxes, typically by either suppressing crystallization or by modifying the growth of crystals so that they are small enough not to impede flow of the base oil or fuel oil through filters or pipes. Such additives are known as wax crystal modifiers and also as cold flow improvers because they improve flow properties at low temperatures. Often a range of additives is needed in order to provide an oil with optimum properties. Thus novel additives and additive formulations are constantly in demand.